I just installed SOHO. I did not install kernel source & Dev tools. Little did I know that I can't install video drivers without them. How do I install them after the fact, or is it easier to completely reinstall SOHO?

You may be able to install them by browsing the CD for the package files and installing via command line (as root, installpkg <name_of_package>). In VL 5.9 Standard they are located in /veclinux/optional, and titled "dev.tlz" and "kernel-src.tlz". Of course, there are probably many more ways of installing those packages.